I have.
I was actually expecting this to be placed in a Periodic tasks, and estimating. I know this code is not likely to take 20ms to execute, and in looking at time-to-execute in loops, it's usually the value wired into the wait function (occasionally plus or minus a millisecond).
As for the packet jitter from the DS, I have done
more detailed testing.
Packets tend to arrive in multiples of 20ms, but and are usually within 2 milliseconds. (This is assuming you're only running the DS and robot for 1 match. Strange things happen over several hours.) Most packets arrive at 40ms (that is to say, half the packets the DS sends aren't received by the robot). It's likely a packet-free period greater than 500ms will occur 10 times within 1 match.
EDIT:
I'm assuming it's inconsequential, but I measured from the loop in Robot Main, and from the DriverStation StartCommunication.vi, not from Teleop itself. The purpose of the tests was to examine the reliability of the Driver Station, not the determinacy of Teleop.vi and RobotMode.vi.